Impact Of Surface Functionalization Research Articles

Polystyrene microplastics as carriers for nano-hydroxyapatite particles: Impact of surface functionalization and mechanistic insights

The potential of microplastics (MPs) to act as carriers for contaminants or engineered nanomaterials is of rising concern. However, directly determining the vector effect of polystyrene (PS) MPs towards nano-hydroxyapatite (nHAP) particles, a typical nano phosphorus fertilizer and soil remediation material, has been rarely studied. In this study, the interaction of differentially surface functionalized PS MPs with nHAP were investigated through batch experiments under different solution chemistry conditions. The results demonstrated that nHAP had the highest attachment/adsorption affinity onto carboxyl-functionalized PS, followed by bare PS and amino-functionalized PS under near-neutral pH conditions. Adsorption of nHAP exhibited a strong pH-dependent behavior with PS MPs, increasing under acidic-neutral pH (3−7) and decreasing at higher pH values. The presence of humic acid and NaCl hindered the adsorption of nHAP onto MPs. Scanning electron microscopy observations revealed a rod-like morphology for adsorbed nHAP, which was randomly distributed on MPs surface. Surface complexation and cation-π interaction were mainly responsible for the adsorption of nHAP as revealed by multiple spectroscopic analyses. These results provide mechanistic insights into nHAP-PS interactions and expound the effect of surface functionalization of PS on binding mechanisms, and thus bring important clues for better understanding the vector effects of MPs towards nanoparticles.

Synthesis, dispersion, functionalization, biological and antioxidant activity of metal oxide nanoparticles: Review

Metal oxide nanoparticles (MONPs) have garnered significant interest due to their remarkable properties with applications in diverse fields like human health, agriculture, and general community health. This has led to their widespread use across various scientific and industrial sectors. We focused on four specific types of MONPs: iron oxide, gadolinium oxide, titanium dioxide, and zinc oxide nanoparticles due to their advantages over other metal oxides and noble metals, including cost-effectiveness, biocompatibility, and versatility. This review aimed to highlight examples of MONPs with various implementations and provide a comprehensive revision on the synthesis, dispersion, functionalization, biological and antioxidant activity of the selected MONPs. In this context, we demonstrated the applications of MONPs in various relevant domains and the impact of surface functionalization on the mechanical, optical, and electrical properties of MONPs, particularly in biological and antioxidant activities. Moreover, the volumetric, viscometric, and optical characteristics of MONPs dispersions and their stability challenges were significantly illustrated. The opportunities for MONPs in the global market based on market statistical studies were introduced in order to explore the current and future prospects for MONPs in the commercial market. This review paper offers a thorough and novel perspective on the synthesis, properties, functionalization, and applications of selected MONPs, along with their market potential, making it a valuable resource for researchers and industry professionals. Our revision has sparked interest in the scientific pursuit of uncomplicated and intuitive ideas that make use of regenerative options.

Impact of Surface Functionality on Biodistribution of Gold Nanoparticles in Silkworms

To date, animal models are still indispensable for studying biodistribution and elimination of nanomaterials. However, the use of mammals for in vivo experiments faces various challenges including increasing regulatory hurdles and costs. This study aims to validate larvae of the domestic silkworm Bombyx mori as an alternative invertebrate model for preliminary in vivo research. Organ distribution and elimination of gold nanoparticles (AuNPs) are compared with four different surface functionalities in silkworms after systemic administration: AuNPs coated with poly(ethylene glycol) (PEG), with polyglycidols (PGs) that are slightly hydrophobic (PG(alkyl)), positively charged (PG(+)), or negatively charged (PG(−)). Subsequent inductive coupled plasma mass spectrometry 6 or 24 h after AuNPs administration reveals the biodistribution in silkworm hemolymph, midgut, epidermis, and excrements. Even after 24 h incubation, hemolymph contains the highest AuNPs concentrations, independent of surface functionalization indicating a prolonged circulation time and slow distribution into different silkworm organs and tissues. Positively charged PG(+)AuNPs show three times higher concentrations in the midgut and are excreted at the fastest rate when compared to other AuNPs. In the findings, a surface‐dependent biodistribution and elimination of AuNPs are indicated in silkworms, and the feasibility of using this inexpensive animal model for time‐ and cost‐effective, preliminary in vivo studies of NPs is confirmed.

Effect and mechanism analysis of surface hydrogenation and fluorination on the electronic properties of th-GeC2.

A two-dimensional (2D) tetrahex-GeC2 nanosheet demonstrates excellent electronic properties such as a finite direct band gap and high carrier mobilities, as predicted from theoretical calculations. To further expand its potential applications, various strategies can be employed to tailor its electronic properties. These strategies include alloying, strain application, and edge and surface functionalization. This work specifically focuses on the impact of surface functionalization with hydrogen and fluorine adsorption on the 2D tetrahex-GeC2 nanostructures. It was discovered that the electronic properties of these nanostructures undergo significant alterations through surface functionalization by adjusting the adsorption sites and coverage of H/F species. The underlying mechanisms responsible for these property changes have been thoroughly analyzed and discussed in detail. Our calculations, based on density functional theory, reveal that the band gap of tetrahex-GeC2 widens as the surface coverage of H atoms increases. Conversely, the band gap narrows in the case of F adsorption. Additionally, the indirect-direct band gap transition can be triggered through surface functionalization. Such modifications in the electronic band structure are primarily due to the disappearance of the π bond when the C atom is converted from sp2 to sp3 hybridization through the adsorption of surface functionalized species. Furthermore, the results indicate that surface adsorption can regulate the effective mass of carriers, electron affinity, and work function in the 2D tetrahex-GeC2 nanostructure.

Impact of Surface Functionalization and Deposition Method on Cu-BDC surMOF Formation, Morphology, Crystallinity, and Stability.

For direct integration into device architectures, surface-anchored metal-organic framework (surMOF) thin films are attractive systems for a wide variety of electronic, photonic, sensing, and gas storage applications. This research systematically investigates the effect of deposition method and surface functionalization on the film formation of a copper paddle-wheel-based surMOF. Solution-phase layer-by-layer (LBL) immersion and LBL spray deposition methods are employed to deposit copper benzene-1,4-dicarboxylate (Cu-BDC) on gold substrates functionalized with carboxyl- and hydroxyl-terminated alkanethiol self-assembled monolayers (SAMs). A difference in crystal orientation is observed by atomic force microscopy and X-ray diffractometry based on surface functionalization for films deposited by the LBL immersion method but not for spray-deposited films. Cu-BDC crystallites with a strong preferred orientation perpendicular to the substrate were observed for the films deposited by the LBL immersion method on carboxyl-terminated SAMs. These crystals could be removed upon testing adhesive properties, whereas all other Cu-BDC surMOF film structures demonstrated excellent adhesive properties. Additionally, film stability upon exposure to water or heat was investigated. Ellipsometric data provide insight into film formation elucidating 7 and 14 Å average thicknesses per deposition cycle for films deposited by the immersion method on 11-mercapto-1-undecanol (MUD) and 16-mercaptohexadecanoic acid (MHDA), respectively. In contrast, the films deposited by the spray method are thicker with the same average thickness per deposition cycle (21 Å) for both SAMs. While the spray method takes less time to grow thicker films, it produces similar crystallite structures, regardless of the surface functionalization. This research is fundamental to understanding the impact of deposition method and surface functionalization on surMOF film growth and to provide strategies for the preparation of high-quality surMOFs.

Exploring optoelectronic properties of undoped and amine-doped carbon dots: Impact of surface functionalization and pH

Tuning optoelectronic properties through surface modifications and doping in low dimensional carbon dots (CDs) has been an asset in designing them for versatile applications. In this article, we explore the modulations in photophysical and charge transport characteristics of doped and undoped CDs functionalized with redox-active dopamine (DA). The pH-dependent DA chemistry on the surface of CDs is observed to have deterring effect on excited state dynamics with superior charge transfer efficiency for pristine CDs compared with the doped one. Charge transport studies through conducting measurements across electrode-CDs-electrode junction report a pH-induced current enhancement with DA functionalization resulting from a shifted equilibrium among the reduced (hydroquinone) and oxidized (quinone) isomers of DA. While the changes in the optical and electronic features are significantly perturbed with pH for the DA-treated undoped CDs, nominal alterations in spectral features are reported for the doped ones. The current-voltage conductance across the junctions is influenced by surface-treated CDs for acidic pH, with signatures of direct tunneling for a low bias regime, curtailing the Fowler-Nordheim (FN) tunneling. These features can have immediate optoelectronic-based applications in pH-based sensors and molecular electronics.

Impact of surface functionalization with phosphate and calcium on the biological performance of Ti-6Al-4V

This study aimed to determine the bioactivities and osseointegration activities of Ti-6Al-4V after surface functionalization with a combination of phosphate and calcium. Several Ti-6Al-4V containing different amounts of phosphate and/or calcium on their surface were prepared. Phosphate was introduced by allowing samples to react with H3PO4, and the resulting phosphate-modified samples were further allowed to react with CaCl2 to obtain phosphate- and calcium-co-immobilized samples. Cell studies revealed that the co-immobilization of phosphate and calcium significantly promoted MC3T3-E1 preosteoblast proliferation and osteogenic differentiation, compared to that in unmodified, phosphate-modified, or calcium-modified Ti-6Al-4V. Furthermore, after implants were inserted into the bone marrow cavity of a rat femur, the osseointegration activity and bond strength between implants and the bone were increased in a phosphate- and calcium-functionalized sample, compared to those in a bare sample.

Impact of Surface Functionalization by Nanostructured Silver Thin Films on Thermoplastic Central Venous Catheters: Mechanical, Microscopical and Thermal Analyses

In this work, an interdisciplinary approach was employed to investigate the impact on thermoplastic catheters from the deposition of a thin (180 nm), metallic silver film by a pulsed ablation technique. Our characterization firstly involved tensile and bending tests, each one accompanied by finite element modeling aiming to elucidate the contributions resulting from bulk and coating to the device’s mechanical behavior. The morphological assessment of the surface before and after the deposition was performed by atomic force microscopy, specifically implemented to visualize the nanostructured character of the film surface and the extent to which the polymer was modified by the deposition process, focusing on coating delamination due to tensile stress. Finally, thermogravimetric–differential thermal analysis was carried out to evaluate whether silver deposition has affected the physiochemical structure of the polymer matrix. Our results establish that the deposition does not significantly alter the physical and chemical properties of the device. The presented characterization sets a useful precedent for elucidating how structural properties of polymeric materials may change after coating by electronic ablation techniques, highlighting the importance of employing a comprehensive approach for clarifying the effects of additive manufacturing on medical devices.

Impact of Surface Functionalization on the Intrinsic Properties of the Resulting Fe–N–C Catalysts for Fuel Cell Applications

Impact of Surface Functionalization on the Intrinsic Properties of the Resulting Fe–N–C Catalysts for Fuel Cell Applications

Impact of surface functionalization on the toxicity and antimicrobial effects of selenium nanoparticles considering different routes of entry

Selenium nanoparticles (SeNPs) were first designed as nutritional supplements, but they are attractive also for use in diagnostic and therapeutic systems owing to their biocompatibility and protective effects. This study aimed to examine if different SeNPs stabilization strategies affect their (i) antimicrobial activity against bacteria Escherichia coli and Staphylococcus aureus and yeast Saccharomyces cerevisiae and (ii) toxicity to human cells of different biological barriers i.e., skin, oral and intestinal mucosa. For surface stabilization, polyvinylpyrrolidone (PVP), poly-L-lysine (PLL) and polyacrylic acid (PAA) were used rendering neutral, positively and negatively charged SeNPs, respectively. The SeNPs (primary size ~80 nm) showed toxic effects in human cells in vitro and in bacteria S. aureus, but not in E. coli and yeast S. cerevisiae. Toxicity of SeNPs (24 h IC50) ranged from 1.4 to >100 mg Se/L, depending on surface functionalization (PLL > PAA > PVP) and was not caused by ionic Se. At subtoxic concentrations, all SeNPs were taken up by all human cell types, induced oxidative stress response and demonstrated genotoxicity.As the safety profile of SeNPs was dependent not only on target cells (mammalian cells, bacteria, yeast), but also on surface functionalization, these aspects should be considered during development of novel SeNPs-based biomedical products.

Impact of Surface Functionalization on the Intrinsic Properties of the Resulting Fe–N–C Catalysts for Fuel Cell Applications

Herein, Fe–N–C catalysts are prepared from surface functionalized carbon nanotubes (CNTs) in combination with iron acetate and phenanthroline. An improved performance and structural composition is obtained by surface functionalization of the CNTs with indazole or pyridine. Catalyst composition and morphology are characterized by transmission electron microscopy, N2 sorption, photoelectron spectroscopy, and 57Fe transmission Mössbauer spectroscopy. However, activity and selectivity toward oxygen reduction reaction are determined from rotating ring disc electrode (RRDE) experiments. The durability and stability are evaluated by accelerated stress tests (0.0–1.2 V) and differential electrochemical mass spectroscopy (DEMS), respectively. It is shown that surface functionalization with indazole enables the direct attachment of FeN4 centers to CNTs so that no impurity species are detected and a high activity is achieved, that can be attributed to an improved turnover frequency and higher mass‐based site density. Even more striking is the excellent durability and stability of the realized catalyst. While these trends are well pronounced in RRDE and DEMS, challenges in the preparation of membrane electrode assemblies make the trend not as obvious in fuel cells (FCs).

The Impact of Surface Functionalization on the Biophysical Properties of Silver Nanoparticles.

Among metal-based nanoparticles, silver nanoparticles (AgNPs) are particularly appealing because of their stability, functionality, and documented antimicrobial properties. AgNPs also offer the possibility of different surface modifications. In this work, we functionalized AgNPs with thiobarbituric acid or 11-mercaptoundecanoic acid residues to improve the nanoparticles’ biological activities. Subsequently, we assessed the physicochemical properties of newly synthesized AgNPs using a wide range of biophysical methodologies, including UV/vis and fluorescence spectroscopy, atomic force and scanning electron microscopy, and dynamic light scattering and isothermal titration calorimetry. Next, we examined the effect of nanoparticles functionalization on AgNPs mutagenicity and toxicity. Our study revealed that AgNPs’ surface modification affects nanoparticles aggregation, and also impacts nanoparticles’ interaction with model acridine mutagen ICR-191. AgNPs coated with MUA showed the most interesting interactions with tested ICR-191, slightly modulating its toxicity properties by decreasing the viability in treated cells.

Adsorption of aromatic carboxylic acids on carbon nanotubes: impact of surface functionalization, molecular size and structure.

A large quantity of emerging contaminants are ionizable, and the ionized compounds display different adsorption behaviors than their neutral counterparts. In particular, a strong intermolecular force, negative charge assisted hydrogen bonding ((-)CAHB), was recently identified, which explains the unusually strong adsorption of negatively charged compounds on carbon nanotubes with oxygen-containing functional groups. However, most previous studies only probed molecules with one benzene ring. The adsorption of ionizable compounds with more than one benzene ring and additional functional groups has not been examined. This study investigated the effect of surface functionalization, molecular size and structure of six aromatic carboxylic acids on their adsorption on multi-walled carbon nanotubes (MWNTs) in batch reactors. In addition, the short-range interactions of the neutral acids with MWNTs were calculated to evaluate the effect of aromaticity and bulkiness. Hydrophobicity and electrostatic interactions dominate the intermolecular forces between ionized contaminants and MWNT surfaces. pH dependent octanol/water partitioning coefficient (Dow) is a more precise indicator of the adsorption of ionizable compounds on MWNTs. (-)CAHB is a significant force only for compounds with one benzene ring. Hydroxyl and carboxyl functional groups displayed similar capacity to form (-)CAHB, as indicated by the release of hydroxide ions.

Impact of Surface Functionalization on the Quantum Coherence of Nitrogen-Vacancy Centers in Nanodiamonds.

Nanoscale quantum probes such as the nitrogen-vacancy (NV) center in diamonds have demonstrated remarkable sensing capabilities over the past decade as control over fabrication and manipulation of these systems has evolved. The biocompatibility and rich surface chemistry of diamonds has added to the utility of these probes but, as the size of these nanoscale systems is reduced, the surface chemistry of diamond begins to impact the quantum properties of the NV center. In this work, we systematically study the effect of the diamond surface chemistry on the quantum coherence of the NV center in nanodiamonds (NDs) 50 nm in size. Our results show that a borane-reduced diamond surface can on average double the spin relaxation time of individual NV centers in nanodiamonds when compared to thermally oxidized surfaces. Using a combination of infrared and X-ray absorption spectroscopy techniques, we correlate the changes in quantum relaxation rates with the conversion of sp2 carbon to C-O and C-H bonds on the diamond surface. These findings implicate double-bonded carbon species as a dominant source of spin noise for near surface NV centers. The link between the surface chemistry and quantum coherence indicates that through tailored engineering of the surface, the quantum properties and magnetic sensitivity of these nanoscale systems may approach that observed in bulk diamond.

Impact of surface functionalization on the uptake mechanism and toxicity effects of silver nanoparticles in HepG2 cells

Safe and successful bioapplications of metallic nanoparticles depend on their physicochemical characteristics, in particular their surface properties. This study aimed to investigate how different surface functionalization of silver nanoparticles (AgNP) affect their interaction with mammalian liver cells with regard to cytotoxicity, genotoxicity and mechanism of cellular uptake. Differentially coated AgNP were prepared by surface functionalization using sodium bis(2-ethylhexyl)-sulfosuccinate (AOTAgNP), cetyltrimethylammonium bromide (CTABAgNP), poly(vinylpyrrolidone) (PVPAgNP), poly-l-lysine (PLLAgNP), and bovine serum albumin (BSAAgNP). Data showed varying toxic potential of differentially coated AgNP. All AgNP types demonstrated concentration dependent effects on cytotoxicity and genotoxicity in HepG2 cells. Cytotoxic potential of differentially coated AgNP followed the order of BSAAgNP > PLLAgNP > CTABAgNP > AOTAgNP > PVPAgNP. Exposure of HepG2 cells to non-cytotoxic concentrations (up to 10 mg Ag/L) of AgNP for 24 h induced primary DNA damage as evaluated by alkaline comet assay. The highest increase in both comet tail length and tail intensity was produced by PLLAgNP followed by AOTAgNP, while CTABAgNP appeared to be least damaging. The main uptake mechanisms of AgNP were macropinocytosis and clathrin-mediated endocytosis. The study findings contribute to the criteria that should be considered in evaluating the biocompatibility and safety of novel nanomaterials.

Magnetic nano-organocatalysts: impact of surface functionalization on catalytic activity

Nano-organocatalysts were synthesized using controlled click chemistry and studied in aldolization and Michael addition reactions. It was shown that small modifications of the nanosurface can have a drastic effect on the catalysis.

Impact of Surface Functionalization on Bacterial Cytotoxicity of Single-Walled Carbon Nanotubes

The addition of surface functional groups to single-walled carbon nanotubes (SWNTs) is realized as an opportunity to achieve enhanced functionality in the intended application. At the same time, several functionalized SWNTs (fSWNTs), compared to SWNTs, have been shown to exhibit decreased cytotoxicity. Therefore, this unique class of emerging nanomaterials offers the potential enhancement of SWNT applications and potentially simultaneous reduction of their negative human health and environmental impacts depending on the specific functionalization. Here, the percent cell viability loss of Escherichia coli K12 resulting from the interaction with nine fSWNTs, n-propylamine, phenylhydrazine, hydroxyl, phenydicarboxy, phenyl, sulfonic acid, n-butyl, diphenylcyclopropyl, and hydrazine SWNT, is presented. The functional groups range in molecular size, chemical composition, and physicochemical properties. While physiochemical characteristics of the fSWNTs did not correlate, either singularly or in combination, with the observed trend in cell viability, results from combined light scattering techniques (both dynamic and static) elucidate that the percent loss of cell viability can be correlated to fSWNT aggregate size distribution, or dispersity, as well as morphology. Specifically, when the aggregate size polydispersity, quantified as the width of the distribution curve, and the aggregate compactness, quantified by the fractal dimension, are taken together, we find that highly compact and narrowly distributed aggregate size are characteristics of fSWNTs that result in reduced cytotoxicity. The results presented here suggest that surface functionalization has an indirect effect on the bacterial cytotoxicity of SWNTs through the impact on aggregation state, both dispersity and morphology.

Interactions between Natural Organic Matter and Gold Nanoparticles Stabilized with Different Organic Capping Agents

The adsorption of natural organic matter (NOM) to the surfaces of natural colloids and engineered nanoparticles is known to strongly influence, and in some cases control, their surface properties and aggregation behavior. As a result, the understanding of nanoparticle fate, transport, and toxicity in natural systems must include a fundamental framework for predicting such behavior. Using a suite of gold nanoparticles (AuNPs) with different capping agents, the impact of surface functionality, presence of natural organic matter, and aqueous chemical composition (pH, ionic strength, and background electrolytes) on the surface charge and colloidal stability of each AuNP type was investigated. Capping agents used in this study were as follows: anionic (citrate and tannic acid), neutral (2,2,2-[mercaptoethoxy(ethoxy)]ethanol and polyvinylpyrrolidone), and cationic (mercaptopentyl(trimethylammonium)). Each AuNP type appeared to adsorb Suwannee River Humic Acid (SRHA) as evidenced by measurable decreases in zeta potential in the presence of 5 mg C L(-1) SRHA. It was found that 5 mg C L(-1) SRHA provided a stabilizing effect at low ionic strength and in the presence of only monovalent ions while elevated concentrations of divalent cations lead to enhanced aggregation. The colloidal stability of the NPs in the absence of NOM is a function of capping agent, pH, ionic strength, and electrolyte valence. In the presence of NOM at the conditions examined in this study, the capping agent is a less important determinant of stability, and the adsorption of NOM is a controlling factor.